Radiation control and minimization system and method

ABSTRACT

A radiation control system and method are provided in which radiation delivered to a patient and/or the operator of the equipment is minimized. The radiation control system may be used in a large variety of applications including applications in which radiation source is used to inspect an object, such as, for example, medical imaging, diagnosis and therapy, in manufacturing operation using radiation, in airports scanning systems, in different security setups, and in nuclear reactors automation and process control. The radiation control system and method may also be used with 3D imaging.

PRIORITY CLAIMS/RELATED APPLICATIONS

This application claims the benefit under 35 USC 119(e) to U.S. Provisional Patent Application Ser. No. 61/453,540 filed on Mar. 16, 2011 and entitled “Radiation Control and Minimization System and Method”, the entirety of which is incorporated herein by reference.

FIELD

The disclosure relates generally to radiation systems (whether for industrial, security, therapeutic use or imaging) and in particular to systems to minimize the radiation to which a patient, a person, an object or an operator is exposed.

BACKGROUND

Devices and system that generate various forms of radiation/ionizing energy are used for various therapeutic/treatment, diagnostic or imaging purposes. For example, various forms of radiation/ionizing energy may be used to inspect an object (such as in airports scanning systems, different security setups, manufacturing and process control) or inspect a patient (such as in a clinic or a hospital, e.g. Cath lab, where a surgeon/therapist operates an X Ray or CT system.)

The medical imaging industry for example is heavily focused on reducing the radiation dose in diagnostic and treatment procedure that include hardware and software modification and operator room procedures. See Miller D L, Baiter S, Schueler B A, Wagner L K, Strauss K J, Vano E. “Clinical radiation management for fluoroscopically guided interventional procedures”, Radiology. November 2010; 257(2):321-332. The reporting of radiation dose is one of the QA measurements that are required by Medicare. Furthermore, the Food and Drug Administration in their 2010 “White paper” called for significant reduction of the “unnecessary radiation”. FDA, “White Paper: Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging. In: Administration CfDaRHUSFaD, ed. 2010.

There are two main components that can reduce radiation exposure. The first component is the technical improvements of the x-ray equipment, such as investment in better filtering, collimators, acquisition equipment and image analysis. The other component is the way the operator uses the radiation, which includes the length of exposure, distance from the source to the patient and proper collimation. See Miller D L, Baiter S, Schueler B A, Wagner L K, Strauss K J, Vano E. “Clinical radiation management for fluoroscopically guided interventional procedures”, Radiology. November 2010; 257(2):321-332 and Arthur W R, Dhawan J, Norell M S, Hunter A J, Clark A L, “Does cardiologist- or radiographer-operated fluoroscopy and image acquisition influence optimization of patient radiation exposure during routine coronary angiography?”, Br J Radiol. September 2002;75(897):748-753. The radiation education of the operator/physician is critical to reduce the radiation dose and trained physician utilize significantly lower amounts of radiation. A similar focus to reduce radiation exposure exists in the non-medical areas. For example, the nuclear industry has been very sensitive for several decades to radiation exposure and in many other manufacturing fields there are strict guidelines for minimizing exposure. See http://www.state.il.us/iema/publications/pdf/IEMA2003EverydayUsesofRadiation.pdf.

For example, during a fluoroscopy guided, interventional medical procedure, there are periods of time when the operator (usually a physician), even when he/she activates the radiation source which radiates the patient and the staff does not receive the information that is generated by a radiation source. This radiation (and the information in it) are not only wasted but are furthermore needlessly damaging to the patient and the staff/operator of the radiation source. This may be referred to as “Unattended Radiation” (UR) which is undesirable. Thus, in the various different applications in which objects or patients are being inspected, it is desirable to reduce the Unattended Radiation and therefore minimize the exposure to the potentially harmful radiation by the operator and/or patient and it is to this end that the disclosure is directed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a medical application in which a radiation source is used to inspect a patient in which unattended radiation may occur;

FIG. 2 illustrates an embodiment of a radiation reduction and minimization apparatus;

FIG. 3 illustrates an example of a gaze direction monitoring device that can be used with the radiation reduction and minimization apparatus;

FIG. 4 illustrates three examples of eye movement tracking attention monitoring devices;

FIG. 5 illustrates a fixation zone tracking implementation of the radiation reduction and minimization apparatus;

FIGS. 6A-6D illustrate different embodiments for controlling the radiation source when fixation zone tracking is used;

FIG. 7 illustrates more details of the controller module for fixation zone tracking; and

FIG. 8 illustrates a brain activity monitoring implementation of the radiation reduction and minimization apparatus.

DETAILED DESCRIPTION OF ONE OR MORE EMBODIMENTS

The disclosure is particularly applicable to a system used to inspect/treat/diagnose a patient in which the radiation is minimized and it is in this context that the disclosure will be described. It will be appreciated, however, that the system and method for reducing radiation exposure has greater utility since it can be used in any application in which it is desirable to minimize the radiation exposure of an object or a person, such as a patient or operator, that can be harmed by that exposure and those applications may include systems that inspect an object in which the operator may be exposed to unneeded radiation (such as airports scanning systems, different security setups, manufacturing and process controls, etc.) or system to inspect a patient (such as in a clinic or a hospital, e.g. Cath lab, where a surgeon/therapist operates an X Ray or CT system, a diagnostic procedure, a treatment procedure, an imaging procedure, etc.) The radiation minimization can be used with any type of radiation including ionizing radiation sources (x-ray, gamma, alpha and beta) and non-ionizing radiation sources (electromagnetic, US). The radiation minimization may also be used with 3D systems such as CT, MRI, Bi-Plane and others.

FIG. 1 illustrates an example of a medical application in which a radiation source is used to inspect a patient in which unattended radiation may occur. In the medical application, a patient 20 may rest on a surface 22 of an apparatus 24. In this example, the apparatus in this example has a radiation source 26 and a detector 28 connected to each other by a C arm 30 wherein the radiation is directed at the patient 20 to image or treat a particular portion of the patient. The apparatus 24 may also include a monitor 32 on which the results of the imaging/treatment of the patient are displayed. The apparatus may also include a radiation activator 34 that allows an operate to activate the emission of radiation from the radiation source. In addition to the patient 20, there may also be an operator 36 (sometimes a physician) and an assistant 38 who are close to the apparatus 24. As a result, the patient, operator and the assistant may also be exposed to radiation and, more particularly, exposed to unattended radiation that is minimized by the radiation reduction and minimization system that is described below. The medical application shown in FIG. 1 is merely representative of the types of system that the radiation reduction and minimization system may be used for since the radiation reduction and minimization system may be used for any system in which it is desirable to be able to reduce/minimize unattended radiation, such as, but not limited to the systems identified above.

FIG. 2 illustrates an embodiment of a radiation reduction and minimization apparatus 40 that can be connected to a radiation generation apparatus 24 in order to reduce/minimize unattended radiation of the radiation generation apparatus 24. The apparatus 40 may be implemented as a combination of hardware elements and software elements that perform the functions and operations described below. In other implementations, the apparatus may be implemented entirely in hardware (a specially programmed hardware device or the like). The apparatus 40 may comprise an attention monitoring module/unit 42 that receives inputs from one or more operator attention monitoring systems 41, that may be implemented using a head and/or brain sensing system, an eye or eyes sensing system or a gaze sensing system that are described below, and generates an attention (e.g., gaze focus) demand signal. The attention demand signal indicates that whoever in operating the radiation generating apparatus 24 has his/her attention appropriately focused, such as directed at/towards the monitor. In more detail, the attention monitoring module/unit 42 and the controller 46 monitors all the users/operators to determine if and when the information generated by radiation is or may be used (e.g., the users/operators read the monitor information) and attention signal is generated. The attention demand signal is fed into a controller module/unit 46.

The operator attention monitoring systems 41 may alternatively include an image analysis and automated identification of a region of interest system. For example, the system can automatically identify the location of a tip of a catheter using well-known image processing techniques (for example identifying the motion of the device that is inside the body, a predetermined geometrical shape of the device and/or a specially marked device) and the direction of the radiation towards this location in order to identify that the operator is alert since the catheter should be at the same location as the radiation. This may be accomplished in several ways including a built in software which performs proper image segmentation and object (say tool/catheter) recognition, followed by reference/access to a pre-loaded medical procedure knowledge (data) base, which will provide the coordinate for the focused radiation (region of high interest). This image analysis and automated identification of a region of interest system can be used with the other attention monitoring systems described above or can be used instead of the attention monitoring systems described above.

The apparatus 40 further may comprise a radiation activation module/unit 44 that receives inputs from one or more radiation activation devices 43, such as the radiation activator 34 in FIG. 1 or any other device that indicate an intent by the operator/assistant to activate the radiation source, and generates a radiation demand signal. The radiation demand signal indicates that the operator has activated the radiation activation devices (indicating intent by the operator/user to initiate radiation) indicating that radiation should be generated. The radiation activation devices may implemented in a variety of ways including a pedal (as shown in FIG. 1), a mechanical switch; a voice command, an optical designation as well as many others that are all can be used with the radiation minimization apparatus since the radiation minimization apparatus is not limited to any particular radiation activation devices. If the radiation activated device has been activated, the radiation demand signal is also fed into the controller module/unit 46.

The controller module/unit 46, based on the radiation demand signal and attention demand signal inputs, activates the radiation generating apparatus in such as way as to reduce/minimize unattended radiation. In particular, the radiation demand signal and the attention demand signal must indicate that the operator's attention is appropriately focused and that the radiation activation device has been activated by the operator. Since both signals must be present in order to activate the radiation generation apparatus, unattended radiation exposure is reduced/minimized. In particular, when the radiation activation device is activated, but the operator's attention is not appropriately focused (based on brain activity monitor and/or detection of the optical focusing by the eye tracking device), it is likely that the operator is not paying attention so no or minimal level (to be determined by the user) radiation is generated by the radiation generation apparatus. Similarly, if the operator's attention is appropriately focused, but the radiation activation device is not activated, the operator likely does not want radiation to be generated so no radiation is generated by the radiation generation apparatus. Thus, the controller module/unit 46 only enables the onset of radiation (using appropriate handshaking and control interface) when both the attention monitoring module and the radiation activation module send an ON signal.

The controller module/unit 46 may also control other aspects of the diagnostic/treatment system. In particular, the controller module/unit 46 may control the patient table 22 based on the attention of the operator. In typical system, most of the time a physician would like to have the center of his attention in the middle/center of the screen/monitor and the physician frequently manually repositions the table and the x-ray tube to achieve it in a typical system. Using the system described herein, the physician, when he/she decided that he/she wants to reposition the table, he/she sends command to the system to adjust table/x-ray tube position to their attention (for example based on their gaze location) and the system can automatically adjust the table. The physician command can be executed by either voice or switch. The operator will have an over-ride switch to turn this option on or off.

When radiation is to be generated by the radiation generation apparatus 24, the controller module/unit 46 may generate one or more radiation control parameters that are used to control the generation of the radiation by the radiation generation apparatus 24. The one or more radiation control parameters may include a location of the radiation (when it is desirable to narrowly focus the radiation on a particular location), timing (the time that the radiation will be generated), frequency (the number of times over a predetermined amount of time that a pulsed radiation beam is generated) and intensity (for radiation generating apparatus in which the intensity of the radiation beam may be adjusted). For example, for an xray, kVP as the energy of the beam is used and mA-density for the intensity of the beam. The parameters may also include the amount of collimation/filtering of the radiation to restrict the beam to the point of attention. Other parameters of importance are the spatial and temporal rates of reduction from the center point with high radiation towards the periphery of the image where smaller (or no) level of radiation may be required.

In configurations with multiple radiation sources aimed at the same target (patient/object), the radiation parameters may also include an identifier of the radiation source to be used (sometimes at different times). Using these one or more radiation control parameters, the controller module/unit 46 can further minimize unnecessary radiation by ensuring that only the necessary amount of radiation for the particular task is used by controlling elements of the radiation generation apparatus such as the electronic grid, filtering, collimation, etc. The one or more radiation control parameters also can be used to ensure that radiation is only directed at a particular location when a particular location can be identified which reduces extraneous radiation on locations that do not need to be irradiated. In addition, the unattended radiation can be blocked using an electrical grid of the radiation source or by placing a shield that blocks the radiation. Now, several examples of situations in which unattended radiation can occur are described, including: 1) a no look, no radiation situation; 2) a “if you cannot use it, do not ask for it” situation; 3) a “where you see if where you get it” situation; and 4) “if you really want it, you will get it” situation.

No Look—No Radiation Situation

In this situation, the operator continues to operate the radiation generating apparatus source while not even looking at the monitor or without his/her attention appropriately focused. The radiation reduction and minimization apparatus described above may be used to remedy this situation in which an operator gaze/look monitoring system is synchronized with a radiation activation device to turn off the radiation generating apparatus if and when the designated operator is not looking at the screen to reduce the radiation exposure of the patient (in medical applications) and/or the operator and other people adjacent the radiation generating apparatus during the operation of the radiation generating apparatus.

In this situation, the attention monitoring devices 41 may be implemented in several different ways. The first implementation of the attention monitoring devices 41 may be a gaze tracking device. The gaze tracking device may be a device that is already commercially available or a customized gaze tracking device and the radiation reduction and minimization apparatus may be used with various types of gaze tracking devices. For example, the gaze tracking devices may include various commercially available eye tracking systems such as those made by SensoMotoric Instruments Inc. (www.smivision.com) and system that can be found at www.sr-reasearch.com/index.html).

Another implementation of the attention monitoring devices 41 may be gaze direction monitoring systems that determine if the operator's gaze is appropriately directed, such as at a monitor. An example of a gaze direction monitoring device that can be used with the radiation reduction and minimization apparatus to remedy this situation is shown in FIG. 3. The radiation reduction and minimization apparatus has the same modules/units shown in FIG. 2 (although not all of the modules/units are shown in FIG. 3). The gaze tracking device in FIG. 3 has a set of goggles/glasses 50 that have a set of sensors and a transmitter/emitter 52 and a set of sensors and a receiver 54 and a reflector 56 on the monitor 32. Alternatively, the transmitter and/or receiver may be attached to the head of the operator. The transmitter sends an electromagnetic energy beam (infrared, radio frequency, laser, etc.) towards the reflector 56 and the reflected energy is received by the receiver 54 to determine if the gaze direction of the operator is towards the monitor 32. When the operator is not gazing at the monitor 32, the energy from the transmitter is not reflected (or the reflected signal does not have a particular characteristic) so that it is determined that the operator is not gazing at the monitor. In this embodiment of the gaze direction monitoring devices, several designs of the emitter-receiver combination may be used including, but not limited to: 1) an emitter and receiver at the visual target and the reflector at the head of the operator; 2) an emitter on the target and the receiver located at the head of the operator; 3) an emitter and receiver at the head of the operator; 4) an emitter at the head of the operator and the receiver on the target; 5) either emitter or receiver or both are located elsewhere in the operational site; 6) silhouette monitoring with regular light or an infrared camera; and 7) three dimensional (3D) image monitoring in which the position of the head will be recorded and the cameras are located on the monitor and can recognize the face and expression of the operator including direction the gaze.

In this situation, the radiation activation module/unit 44 has the same elements and operation as described above in FIG. 2. The controller module/unit 46 also has the same elements and operation as described above in FIG. 2. In this situation, the apparatus prevents radiation exposure when the operator is not appropriately focused or looking at/towards the monitor 32.

An example of this situation occurs in a catheterization lab. In particular, live/continuous fluoroscopy is routinely used to perform minimally invasive surgical procedures in order to facilitate the navigation inside the human body. Guided by the live/continuous fluoroscopy and using the small radiopaque (visible under x-ray) equipment (catheters, balloons, stents, coils), the operator can navigate inside the human body and deliver the treatment to the specific location. Typically, the radiation source is activated by the user/operator, commonly by switch/foot pedal, which activates the radiation source (x-ray tube), which in turn generates the x-rays. The x-rays then pass the object/patient and the detector camera receives the information. The information is then presented on the monitor for the analysis by the user/operator. In many cases these surgical procedures demand significant mental concentration and attention to the details. In these cases the operator can be distracted by the complexity of the procedure and continues to operate x-ray equipment while not looking at the monitor. This results in “unnecessary” radiation that doesn't provide the information to the operator, significantly increasing the radiation dose that is harmful to the patient and to the operator. The radiation reduction/minimization systems reduces this unnecessary radiation.

While the foregoing has been with reference to a particular embodiment of the invention, it will be appreciated by those skilled in the art that changes in this embodiment may be made without departing from the principles and spirit of the disclosure, the scope of which is defined by the appended claims. 

1. An apparatus for tracking of operator attention for medical radiation optimization, comprising: an attention monitor device that senses, in real time, a focus of attention of an operator of a medical radiation system to generate a sensed attention monitoring signal; a signal processor that signal processes the sensed attention monitoring signal to determine the focus of attention of the operator of the medical radiation system; and a medical radiation system whose radiation is stopped when the focus of attention of an operator of a medical radiation system is not on a monitor of the medical radiation system.
 2. The apparatus of claim 1, wherein the attention monitor device is one of a head posture monitor, a gaze tracking monitor, a gaze direction monitor and a mental attention monitoring device.
 3. The apparatus of claim 1, wherein the attention monitor device is a set of eyewear for the operator having a transmitter and a receiver and a reflective coating on the monitor wherein a signal from the transmitter reflects off of the reflective coating on a monitor when the user attention is on the monitor and is received by the receiver.
 4. The apparatus of claim 1, wherein the attention monitor device is a device worn on the head of the operator having a transmitter and the monitor having a receiver wherein the transmitter and the receiver communicate with each other to determine the focus of attention of the operator.
 5. A method for tracking of operator attention for medical radiation optimization, the method comprising: sensing, by an attention monitor device, in real time if an operator of a medical radiation system is focused on a monitor of the medical radiation system to generate a sensed attention monitoring signal; signal processing, using a signal processor connected to the attention monitor device, the sensed attention monitoring signal to determine if the operator of the medical radiation system is focused on the monitor of the medical radiation system; and controlling the radiation of a medical radiation system based on the focus of the operator on the monitor of the medical radiation system
 6. The method of claim 5 wherein sensing the focus of attention further comprises sensing the focus of attention using one of a head posture monitor, a gaze tracking monitor, a gaze direction monitor and a mental attention monitoring device.
 7. The method of claim 5, wherein sensing the focus of attention further comprises using a set of eyewear for the operator having a transmitter and a receiver and a reflective coating on a monitor wherein a signal from the transmitter reflects off of the reflective coating on a monitor when the user attention is on the monitor and is received by the receiver.
 8. The method of claim 5, wherein sensing the focus of attention further comprises using a device worn on the head of the operator having a transmitter and a monitor having a receiver wherein the transmitter and the receiver communicate with each other to determine the focus of attention of the operator. 